feat(data): TaskRepository.CreateChildAsync

src/ClaudeDo.Data/Repositories/TaskRepository.cs

@@ -217,6 +217,56 @@ public sealed class TaskRepository
             .ToListAsync(ct);
     }
 
+    public async Task<TaskEntity> CreateChildAsync(
+        string parentId,
+        string title,
+        string? description,
+        IReadOnlyList<string>? tagNames,
+        string? commitType,
+        CancellationToken ct = default)
+    {
+        var parent = await _context.Tasks.FirstOrDefaultAsync(t => t.Id == parentId, ct);
+        if (parent is null)
+            throw new InvalidOperationException($"Parent task {parentId} not found.");
+
+        var maxSort = await _context.Tasks
+            .Where(t => t.ListId == parent.ListId)
+            .Select(t => (int?)t.SortOrder)
+            .MaxAsync(ct);
+
+        var child = new TaskEntity
+        {
+            Id = Guid.NewGuid().ToString(),
+            ListId = parent.ListId,
+            Title = title,
+            Description = description,
+            Status = TaskStatus.Draft,
+            CreatedAt = DateTime.UtcNow,
+            CommitType = string.IsNullOrEmpty(commitType) ? parent.CommitType : commitType,
+            ParentTaskId = parentId,
+            SortOrder = (maxSort ?? -1) + 1,
+        };
+        _context.Tasks.Add(child);
+
+        if (tagNames is not null && tagNames.Count > 0)
+        {
+            foreach (var tagName in tagNames.Distinct(StringComparer.OrdinalIgnoreCase))
+            {
+                var tag = await _context.Tags.FirstOrDefaultAsync(t => t.Name == tagName, ct);
+                if (tag is null)
+                {
+                    tag = new TagEntity { Name = tagName };
+                    _context.Tags.Add(tag);
+                    await _context.SaveChangesAsync(ct);
+                }
+                child.Tags.Add(tag);
+            }
+        }
+
+        await _context.SaveChangesAsync(ct);
+        return child;
+    }
+
     #endregion
 
     #region Queue selection